How to install Gravity Forms: Remove required and add optional string to increase form submits plugin:
Go to Wordpress admin area and click "Plugins" and then "Add New" menu item.
In the right panel (left top) you will see "Upload Plugin" button. Click the button.
Next click the "Choose file" button in right panel (center).
Select zip file of the "Gravity Forms: Remove required and add optional string to increase form submits" plugin located on your hard drive and press "Open".
Click "Install Now" and the zip file will upload to your site.
Now click "Activate" button to activate the "Gravity Forms: Remove required and add optional string to increase form submits" plugin.
We've tested following plugins published by: Online Boswachters